Underground and surface pipes, either potable water pipes, waste water pipes or sewer pipes, are typically made of rigid materials such as reinforced concrete, cast iron, ductile iron, steel and hard polymers such as PVC, HDPE, etc., that are durable and adapted to resist internal fluid pressure and the external pressure of the weight of the soil above them. Underground and surface pipes networks provide essential services to homes and businesses and have been deployed in cities, towns and villages for more than a century. Buried and surface pipes connected together in a network extends over long distances, spreads out in all directions to provide services to residential homes or businesses over a wide area. Underground and surface pipes are subject to normal wear and degradation over extended periods of time due to cyclical loads, earth movements, corrosion, increased porosity, cracks and overall deterioration. As a result of their long service life, underground and surface pipes will become damaged and require repair or replacement.
Replacement of damaged sections or portions of a pipe network is an expensive, disruptive and time-consuming operation requiring heavy equipment for accessing, removal and replacement. Replacing older networks of underground water conduits with new ones is unrealistic because of the sheer magnitude of the work that would be involved and is avoided as much as possible. However, repairing and rehabilitating existing water networks without the need to excavate represents a feasible alternative. Methods exist for repairing the walls of pipes and other conduits. One such method involves the use of a tubular liner impregnated with a cured-in-place resinous material, referred to as cured-in-place pipe (CIPP) which re-lines the inner walls of the conduit or pipe to repair the network of conduits or pipe. The liner is impregnated with a resin capable of curing and hardening to form a new inner wall for the aging or damaged pipes. A length of CIPP liner is inserted in the conduit or pipe and is pulled inside the conduit or pipe through a specific segment of the conduit or pipe from one entrance point to an exit point. Once in place, pressurized water is introduced inside the CIPP liner to press the CIPP liner against the pipe wall. The resin is then allowed to cure and harden, thereby creating a new sealed interior pipe wall.
The tubular liner is typically a flat textile material or felt material which is rolled into tubular form and stitched along its seam or a seamless tubular textile jacket made of warps and wefts woven into tubular form. When the tubular liner inserted into the entrance point of the conduit or pipe and pulled inside the segment of the conduit or pipe to be rehabilitated, the tubular liner often drags on the edge of the conduit's entrance opening thereby increasing the force required to pull the length of tubular liner through the segment of the conduit or pipe. In the process, the tubular liner end up being stretched unevenly over its length, it may form folds and wrinkles and it may get damaged.
Tubular liners made of rolled material stitched along the seam are particularly vulnerable as the seam is the weak portion of the tubular liner and the stitches may break under load thereby ripping the tubular liner at the seam and creating gaps which render the rehabilitation of the underground or surface pipe ineffective. Seamless tubular textile jackets are stronger because they do not have a seam that can be torn apart. However, seamless tubular liners may be unevenly stretched or wrinkles, bulges and/or folds may be formed when the seamless tubular liner is pulled and dragged on the edge of the conduit's entrance opening and the quality of the rehabilitation liner once cured may be affected.
Thus, there is a need for a method and an apparatus for inserting a tubular liner into a host conduit or pipe to be rehabilitated that prevents stretching, wrinkling, bulging, folding or damaging the tubular when it is pulled inside the host conduit or pipe.